When a module fails before entering its reactor loop, propagate
the error back to "flux module load" so the user knows the
load was not successful.

Address memory leaks and adjust KVS usage to ameliorate increasing
broker memory footprint and degrading job throughput when running
many small jobs back to back. Active jobs are now stored under
"lwj-active" to avoid creating excessive versions of the larger lwj
directory as job state is accumulated.

Bug fixes to "live" (TBON self-healing) module. The module is no
longer loaded by default, pending additional work. flux up will
always report all ranks up when live is not loaded.

Send keepalives on the ring network and log idle peers on TBON
and ring at LOG_CRIT level, where "idle" means no messages in >= 3
heartbeats.

Compress large content-sqlite blobs with lzo to reduce disk
utilization.

KVS improvements:

kvs_put() follows intermediate symlinks

KVS operations bundled within one commit are applied in order

add kvs_copy() and kvs_move() utility functions.

Configuration is loaded into broker attribute "config" namespace
rather than KVS, and is no longer inherited from the enclosing instance.